Optical networks are evolving to mesh networks. In the existing technology, nodes in the optical networks are below 4 dimensions, whereas in the future, nodes in the optical networks will evolve from 2-3 dimensions to 4-5 dimensions, or even more dimensions. This requires advanced optical switching technology.
Currently, granularity in optical switching mainly depends on wavelength exchange, which requires that the optical switching device should have 100% Add/Drop capability. That is, the ratio of the number of Add/Drop wavelengths to the number of the wavelengths input by the optical switching device is required to be 100%. In addition, colorlessness is also required for the optical switch device. Colorlessness indicates that the optical switch device can achieve exchange of light with various wavelengths rather than only light with specific wavelengths.
FIG. 5 shows the structure of an optical switching device provided in the prior art. The working principles of the device are as follows: An optical splitter 31 splits a beam of light into more than one beam of light and drops some beams of light to the local, and a wavelength blocker (WB) 32 selects the wavelengths of other beams of light that needs to pass, and an optical splitter 33 inputs the beams of light, obtained by splitting and dropped to the local, into a tunable filter array 34, where the output port of the tunable filter array 34 can selectively implement the dropping of light with any wavelength. The optical splitter 33 may be a 1×N optical splitter. That is, a beam of light is split into n beams of light. More than one beam of light to be added is combined, by an optical splitter 35, into one beam of light, input into an optical splitter 36, and converges with the output light that passes through the WB 32. The light split by the optical splitter 36 is combined by an optical combiner 37. FIG. 5 shows an optical switching device featuring colorlessness. An optical multiplexer is provided to implement colorless adding of light with various wavelengths. However, the optical switching device in FIG. 5 has the following problems: The tunable filter has high insertion loss, and the costs is high.